fix(rdb): null-guard view/function/procedure list endpoints

[Aias00]

What

DbFunctionController, DbProcedureController, and DbViewController list endpoints called .size() directly on the service/converter result, NPEing when it returned null (some JDBC drivers return null for empty result sets). DbTriggerController already guards with CollectionUtils.isNotEmpty.

Location

• DbViewController.java:53-57
• DbFunctionController.java:38-42
• DbProcedureController.java:38-42
• DbTriggerController.java:39-43 (reference, already guarded)

Fix

Align the three unguarded controllers with a null-safe size computation (compute size only when non-null). Mirrors DbTriggerController's intent without adding an import. Real DB-level pagination is a separate feature.

Verification

• Long.valueOf(size) where size is an int; 1/size autobox to Integer for of(List, Long, Integer, Integer).
• No NPE when the service/converter returns null.

Refs #2403

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR fixes a null-handling bug in the RDB metadata “list” endpoints for views, functions, and procedures. Previously, these controllers called .size() on potentially null lists (some JDBC drivers can return null instead of an empty list), causing NPEs; the change aligns their behavior with the already-null-safe trigger endpoint pattern.

Changes:

• Add null-safe size computation in DbViewController.list, DbFunctionController.list, and DbProcedureController.list.
• Preserve existing “fake pagination” behavior while ensuring WebPageResult.of(...) is constructed without dereferencing a null list.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
chat2db-community-server/chat2db-community-web/src/main/java/ai/chat2db/community/web/api/controller/DbViewController.java	Null-guards the converted view list before computing size/total for WebPageResult.
chat2db-community-server/chat2db-community-web/src/main/java/ai/chat2db/community/web/api/controller/DbProcedureController.java	Null-guards procedure list before computing size/total for WebPageResult.
chat2db-community-server/chat2db-community-web/src/main/java/ai/chat2db/community/web/api/controller/DbFunctionController.java	Null-guards function list before computing size/total for WebPageResult.

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[openai0229]

Reviewed the null normalization across the three metadata list endpoints after syncing with the latest main. The Web module packages successfully. This PR only addresses the null-result NPE; the description now uses Refs #2403 so the still-open result-cap/pagination work is not closed incorrectly.